Star Trek style pneumatic doors that don’t require a stagehand

In 1966, [Gene Roddenberry] introduced fully manual doors powered by a stagehand on Star Trek. The fwoosh sound of the door was later dubbed into each show, but progress marches on, and now [Alex] created his own Star Trek-style automatic doors for his house.

The build includes a ‘control panel’, and [Alex]’s door operates in three modes: Open, and stay open; Close, and stay closed; and Automatic. The control panel itself is fairly remarkable. A small puck interacts with a magnetometer underneath [Alex]’s counter. If the puck is pointed towards ‘Open’, the door stays open. If the door is pointed towards ‘Closed’, the door stays closed. If the puck isn’t near the magnetometer, the door operates in automatic mode with the help of a few IR sensors to detect someone trying to get in or out of [Alex]’s kitchen.

For the mechanical portion of the build, [Alex] used a One meter long piston with the quietest air compressor he could find. We can’t tell from the video after the break if the compressor ever kicks in, but [Alex] says it’s about the same volume as his fridge. As a small added bonus, the new automatic door does have a fwoosh sound, just like [Gene] would have wanted.

When/if I ever construct a home it will have some packet doors, but manually operated. Perhaps I missed it, but I can’t recall a mention of a fail safe way to open the door,if the pneumatic operation fails operation fails. Respectfully not near the Star Trek sound effects, All I hear is the air coming out the valve’s relief port, at the end of the piston travel. Far out build non the less.

Isn’t the time you need a safety feature the most when the door is traveling. In particular, when it is traveling shut? As-is, what happens when you stand in the door frame when it starts to shut? Really curious :)

Power failure really didn’t enter my mind. Alex. What entered my mind was any failure mode that doesn’t leave the relief ports open. With the relief port not open you will be trying to compress air as you try to push the door manually.

I happen to design products for the door industry. I don’t work in automatic sliding doors, but I’m aware of how they’re built and the standards they must meet.

Alex’s design is not more complicated than a commercial sliding door. It’s probably less expensive, too. It’s also quieter and more elegant. It can be, because that little wooden door weighs a lot less than the big glass doors you’re used to seeing.

It’s also built with such complete disregard for entrapment protection that, being American, I’m scared to be held liable for saying anything nice about it at all. Or for giving advice beyond don’t try this at home, and no, adding “safety beams” isn’t nearly enough!

Most likely, he’s referring to contact-resistance, wherein if the door encounters something that would hinder it’s movement (either open or closed), it would automatically stop and try to reverse itself, or it can simply stay in place.

Pretty nice build. The door operates nicely, but seems to be a bit slow to start opening, he almost walked into it!
Not sure I understand the whole “puck” thing on the counter. Kinda weird, maybe that should be ON the door, or near it? It’s neat, but weird.

As some have mentioned before, you should also include some type of ‘all clear’ sensor like garage doors have. It should be easy enough to just get another IR sensor like you already have and mount it 6″ off the ground or so and interface it to the Arduino.

Britt really, for practicality? electric window motors with chain drive…if you want to wait a long time like a garage door then ok. but for speed, air looks like a better option.

you may almost have something with car window motors. you could use car window scissor design to open and close the door. wouldn’t need much more extra space for it. and then possibly electric motor. but not chain drive.

But like this project and others I’ve seen. The star trek swoosh sound comes naturally from the air. Electric motors sounds are not the sounds you want..

I agree with pRoFlT. Having fabricated projects involving all kinds of drive systems, I can tell you from experience that pneumatic is just about the simplest, quietest, quickest, safest, and most reliable methods out there.

and btw – why in god’s name would you NOT use a linear actuator for this ? i know, they lock in position when they lose power, but it would be a simple matter to have a manual release in that case, or a simple battery backup. that compressor alone is simply fucking ridiculous over engineering for a simple problem.

I thought about an powered solution for a pocket door a couple of years ago, but dropped it after considering the safety, noise, expense and installation. My beef with pocket doors was the difficulty in pulling them out of the pocket and opening them from full closure. I solved both problems with a spring release at both ends. Tapping on the foot pad when the door is open pops it out of the pocket. Turning the inset latch handle pops it away from the door jam when it is closed. It doesn’t go whoosh, but after a couple of years, it is still a pleasure to use.

^Your comment got me thinking… I wonder if a ball-screw(such as might be used in the gantry of a CNC machine)could be used with a high speed motor to move the door quickly. Of course, there would need to be some type of emergency release, as commented above…

Cool door!
My guess is that those pistons aren’t strong enough to pose much of a safety threat besides maybe slamming your finger in the door. Now he needs a star trek style panel next to the door, and have it open when you yell “come”.

My $.02
While a “light curtain” or beam might be a good addition, the air pressure can be set at the regulator to adjust closing force. So light that door could stick during movement, although the decreased pressure also affects opening/closing speed. If adjusted right, the door closing on you would be no worse than if it were a spring loaded door. Also by reading his comments, the piston has no pressure on it while not moving, so the door can be easily slid when not automated.

To make it slightly more complicated, but make it adaptable, I would use a shorter stroked piston in a vertical arrangement, linked to a lever that slides verticals along the edge of the door. With a pivot point 1/4 way towards the piston, you could move a 36″ door with a 9″ piston, have more speed with less force applied at the door. Although the piston would require more pressure. It would also use less space.

Although the Arduino is a little overkill, especially if left hooked up permanently. An AtTiny could do the same job as well, even analog parts, but it is all in what you are familiar with. I think I would find another interface as well, in my house the cat would run off with the puck…

I could always find an additional use for an air compressor. From basics like airing up tires and blowing out equipment to using it as a power source for additional automation. First thing that comes to mind in a kitchen would be a trash compactor, second might be an automatic fridge door to open in case your hands are full with a bump of a button.

In other words Bravo, you’re several steps ahead of me. I only think of how to do projects, occasionally start them and rarely finish them.

Alex, this is great. Guys give the dude a break on the tech details. Having the will do build something like this is NOT only a hard core display of geek. It is a huge sacrifice on one’s purchasing power, which no offense Alex, is horrible in UK on the soil of %20 sales tax (or VAT whatever that is) and horribly overpriced everything (being EU and all).

Guys have you looked at how much this stuff costs? OMG OMG. That compressor is $45 at home depot.

Dude we live in the UK not some 3rd world country. Their’s ton’s of stuff to buy thats cheap for projects over here. Ever heard of ebay? I bought 3 ardunio boards for a project for £10 including delivery. At least were not pepper spraying people for discount xboxs…

Wicked project Alex, That sound alone makes having a door like that worthwhile. If you wanted a bit more safety just incase of kids etc. you could attach a G-meter to measure for impacts outside of its normal operation, and have it stop via the arduino.

- Nice job Alex! My apologies for the bunch of whiners you have to listen to in here. This is hacking, not safety hour. Home built hacks are not supposed to be safe. We assume our own risks. We make devices as we see fit to our own standards and likings, not to be mass produced to the public (generally). For the whiners on safety, costs, and methods /materials used, feel free to NOT do the project yourself and NOT ever come visit us to see or use them.

Ah great point, I forgot to explode on all the safety BS. Are you kidding me? Safety? From what? What do you think is the bone crunching pressure exerted by 30-80 PSI with a piston in such a small diameter and zero acceleration by a door that weights 70 lbs? Are you kidding me? One is in much more danger by a door slammed at one’s face by a GF resulting from a well-meant but sadly inappropriate joke. Come on…..

Without making assumptions about this build. So why aren’t hacks supposed to be safe? Perhaps that’s not exactly what you meant, but that’s what you wrote. Building to substandard personal standard is is fine if one lives in a bubble, and you retain ownership of a build or modified item, but that’s rarely the case. Good thing Hackaday, and similar aren’t widely read. Comments provide great ammo to those who aren’t DIY friendly.

Actually, I wrote: “If you hack something together, you aren’t initially focused on safety, you’re focused on accomplishing the goal.

That merely means that you are first trying to achieve something. Safety may come later. This site is, in large part, about repurposing something and making it provide another function. This is NOT necessarily taking a product to market. This site focuses on spotlighting projects that will most likely NEVER see market in any form. If they do however, they will be redesigned and safety will become a higher priority.

If you wish to prioritize safety in your own projects, more power to you. I would only ask that you stop judging others’ projects on whether or not they have considered safety to your satisfaction.

I’m curious as to what you mean by the non DIY-friendly crowd. I wouldn’t worry about the people protesting those of us who like to do things ourselves. Not sure I really care.

For a simple anti-crush safety you can use a pressure sensor on the closing air line. If it goes above the normal pressure required to close the door it opens back up. That would be the air-analogue of the electrical sliding doors I have worked on.

Also if you cant find a cylinder with that long of a stroke you can use a shorter cylinder and use a series of pulleys to multiply the travel.

I’m having a difficult time wrapping my mind around how a pulley arrangement can increase the effective stoke of a cylinder. A pulley suggest the use of a line. The use of one pulley means that twice the line needs to be taken up to move an object the same distance if a pulley wasn’t used. Then again I’m not a rigger.

If one side of the rope is stationary, and the other side is tied to the door, the end of the piston holds the pulley and the pulley moves. 6″ of piston/pulley stroke moves 12″ of rope. Using a block and tackle arrangement would give an even larger ratio.

The only problem is you would either have to have the door spring loaded to pull the other way, Have 2 pistons (one for each direction) or do a lot of rope rigging to reverse direction since rope doesn’t push well.

By saying side of the rope, I assume you mean end end of the rope. All I can see that arrangement doing is moving the door 6″. The only rope movement would be the straight line pull on the door, with no rope traveling over the pulley.

That way you have access to centuries of ideas, and when not for commercial use you can use it, or it makes you think of your own version of doing things. I find it fascinating to see how many clever ideas there are, and they all have drawings, although half the time I can’t make head or tails of them I must admit :)

@nolkk
The thing about a block and tackle is that you have to consider that you can use either working end. The typical arrangement is the one you described where you have a heavy load that you want moved and you cut the force in half will doubling the pull. But you can flip that around as well. If you have a length of pull that you need, you can double the force and halve the pull length on the other end. Basically you apply work to the traditional weight end.

I understand the reciprocal your are explaining, but it doesn’t work(work well anyway) with the example Trav gave. The only place for the pulley is at the cylinder, in that example is at the cylinder. With one end of the line attached to the door and the other end dead somewhere 6″ of cylinder travel is going to move the door 6″. Even if you put in a 12″ length of line, the cylinder will have to move 6″ just to bring the line taut. More a pulleys to make it work combined. with a slack line( a 24″ door will need 24″ slack line) sounds, like a mess waiting to appear at an inopportune time. Air cylinders are easy, and cheap to build at home. Just don’t tell nobody you used PVC pipe. ;)

pull pulley back 3′-
9′ string between dead end and pulley. That leaves 3′ between pulley and door. That leaves the door at the place the pulley started 6′ from the dead end. Moved twice as far as the pulley.

But you are right there is a chance of mess if slack comes in the line, but you design it so that is limited. But for the most part cylinders are easier if they are available in the size needed.

generally I don’t have problem with flowing air, electrons, and fluid, or most mechanical motion but give me a rope I’m likely to hang myself. I drew it out on paper the first time you mentioned it, and again when I responded to the other person who tried to assist, now doing so again it finally registered. Must be true about they say about the third time being a charm. Thanks for patience.

Cool! I welded up a fantasy sci-fi door, but never got around to automating it. It ended up quite heavy anyway, so I decided it must not be Federation tech, maybe Klingon. I installed a laser pointer with the beam running along the forward edge, with the idea of being able to detect any object or body part that was about to get smashed, with the idea of implementing an emergency stop; that’s as far as I got with the electronics, and I didn’t know where to find such a long air cylinder on the cheap, either. The roller-rail I used is quite noisy itself (the barn door type) so it wouldn’t ever sound like an Enterprise door (well maybe for the cargo bay). But yours is more like the door to ten-forward. ;-)

Oh right my first motorized sliding door was the one in my 1949 28-foot trailer, which I lived in while I was at college and then the university (1989-1995). The wood sliding door was already there; I motorized it with junk I had lying around: a windshield wiper motor with a toothed pulley on it, and I only had a couple feet of matching toothed belt so I joined the belt and a piece of rope together. On one end of the door was the motor and on the other was a little v-belt pulley (for the rope). I attached the door to the belt with a little metal bracket. Then I wired up a couple of limit switches and a DPDT rocker switch in such a way that I could flip it one way to open the door and the other to close. So no need for any electronics at all, it was purely electromechanical. I positioned the limit switches experimentally so that the door would not slam at either end (the motor had a bit of momentum). Not sure if I ever took a picture since that was before digital cameras were easily available…

You won’t believe that, but fridge compresors are as quiet as fridge :-D And you can get them for free! They need just simple modifications to get running outside the fridge (proper wiring an plumbing). However they have som auto shutoff feature (probably based on bimetal thermostat), so they don’t run non-stop. so if you need higher pressure, you may need two of them…

Airbrush compressors, which can get fairly large, are very quiet. I have one which is quite a bit quieter than a refrigerator. It sounds more like a fish tank. (a quiet one). Mine gets enough pressure to operate a nail gun 3 or four times before it powers up again to rplenish the 1 gallon tank.